The impact of adjuvant therapy on contralateral breast cancer risk and the prognostic significance of contralateral breast cancer: a population based study in the Netherlands

Second Primary Breast Cancer in Young Breast Cancer Survivors

Importance

Among women diagnosed with primary breast cancer (BC) at or younger than age 40 years, prior data suggest that their risk of a second primary BC (SPBC) is higher than that of women who are older when they develop a first primary BC.

Objective

To estimate cumulative incidence and characterize risk factors of SPBC among young patients with BC.

Design, Setting, and Participants

Participants were enrolled in the Young Women's Breast Cancer Study, a prospective study of 1297 women aged 40 years or younger who were diagnosed with stage 0 to III BC from August 2006 to June 2015. Demographic, genetic testing, treatment, and outcome data were collected by patient surveys and medical record review. A time-to-event analysis was used to account for competing risks when determining cumulative incidence of SPBC, and Fine-Gray subdistribution hazard models were used to evaluate associations between clinical factors and SPBC risk. Data were analyzed from January to May 2023.

Main Outcomes and Measures

The 5- and 10- year cumulative incidence of SPBC.

Results

In all, 685 women with stage 0 to III BC (mean [SD] age at primary BC diagnosis, 36 [4] years) who underwent unilateral mastectomy or lumpectomy as the primary surgery for BC were included in the analysis. Over a median (IQR) follow-up of 10.0 (7.4-12.1) years, 17 patients (2.5%) developed an SPBC; 2 of these patients had cancer in the ipsilateral breast after lumpectomy. The median (IQR) time from primary BC diagnosis to SPBC was 4.2 (3.3-5.6) years. Among 577 women who underwent genetic testing, the 10-year risk of SPBC was 2.2% for women who did not carry a pathogenic variant (12 of 544) and 8.9% for carriers of a pathogenic variant (3 of 33). In multivariate analyses, the risk of SPBC was higher among PV carriers vs noncarriers (subdistribution hazard ratio [sHR], 5.27; 95% CI, 1.43-19.43) and women with primary in situ BC vs invasive BC (sHR, 5.61; 95% CI, 1.52-20.70).

Conclusions

Findings of this cohort study suggest that young BC survivors without a germline pathogenic variant have a low risk of developing a SPBC in the first 10 years after diagnosis. Findings from germline genetic testing may inform treatment decision-making and follow-up care considerations in this population.

External validation and clinical utility assessment of PREDICT breast cancer prognostic model in young, systemic treatment-naïve women with node-negative breast cancer

BACKGROUND

The validity of the PREDICT breast cancer prognostic model is unclear for young patients without adjuvant systemic treatment. This study aimed to validate PREDICT and assess its clinical utility in young women with node-negative breast cancer who did not receive systemic treatment.

METHODS

We selected all women from the Netherlands Cancer Registry who were diagnosed with node-negative breast cancer under age 40 between 1989 and 2000, a period when adjuvant systemic treatment was not standard practice for women with node-negative disease. We evaluated the calibration and discrimination of PREDICT using the observed/expected (O/E) mortality ratio, and the area under the receiver operating characteristic curve (AUC), respectively. Additionally, we compared the potential clinical utility of PREDICT for selectively administering chemotherapy to the chemotherapy-to-all strategy using decision curve analysis at predefined thresholds.

RESULTS

A total of 2264 women with a median age at diagnosis of 36 years were included. Of them, 71.2% had estrogen receptor (ER)-positive tumors and 44.0% had grade 3 tumors. Median tumor size was 16 mm. PREDICT v2.2 underestimated 10-year all-cause mortality by 33% in all women (O/E ratio:1.33, 95%CI:1.22-1.43). Model discrimination was moderate overall (AUC10-year:0.65, 95%CI:0.62-0.68), and poor for women with ER-negative tumors (AUC10-year:0.56, 95%CI:0.51-0.62). Compared to the chemotherapy-to-all strategy, PREDICT only showed a slightly higher net benefit in women with ER-positive tumors, but not in women with ER-negative tumors.

CONCLUSIONS

PREDICT yields unreliable predictions for young women with node-negative breast cancer. Further model updates are needed before PREDICT can be routinely used in this patient subset.

Risk of second primary cancer among women in the Kaiser Permanente Breast Cancer Survivors Cohort

BACKGROUND

Breast cancer survivors are living longer due to early detection and advances in treatment and are at increased risk for second primary cancers. Comprehensive evaluation of second cancer risk among patients treated in recent decades is lacking.

METHODS

We identified 16,004 females diagnosed with a first primary stage I-III breast cancer between 1990 and 2016 (followed through 2017) and survived ≥ 1 year at Kaiser Permanente (KP) Colorado, Northwest, and Washington. Second cancer was defined as an invasive primary cancer diagnosed ≥ 12 months after the first primary breast cancer. Second cancer risk was evaluated for all cancers (excluding ipsilateral breast cancer) using standardized incidence ratios (SIRs), and a competing risk approach for cumulative incidence and hazard ratios (HRs) adjusted for KP center, treatment, age, and year of first cancer diagnosis.

RESULTS

Over a median follow-up of 6.2 years, 1,562 women developed second cancer. Breast cancer survivors had a 70% higher risk of any cancer (95%CI = 1.62-1.79) and 45% higher risk of non-breast cancer (95%CI = 1.37-1.54) compared with the general population. SIRs were highest for malignancies of the peritoneum (SIR = 3.44, 95%CI = 1.65-6.33), soft tissue (SIR = 3.32, 95%CI = 2.51-4.30), contralateral breast (SIR = 3.10, 95%CI = 2.82-3.40), and acute myeloid leukemia (SIR = 2.11, 95%CI = 1.18-3.48)/myelodysplastic syndrome (SIR = 3.25, 95%CI = 1.89-5.20). Women also had elevated risks for oral, colon, pancreas, lung, and uterine corpus cancer, melanoma, and non-Hodgkin lymphoma (SIR range = 1.31-1.97). Radiotherapy was associated with increased risk for all second cancers (HR = 1.13, 95%CI = 1.01-1.25) and soft tissue sarcoma (HR = 2.36, 95%CI = 1.17-4.78), chemotherapy with decreased risk for all second cancers (HR = 0.87, 95%CI = 0.78-0.98) and increased myelodysplastic syndrome risk (HR = 3.01, 95%CI = 1.01-8.94), and endocrine therapy with lower contralateral breast cancer risk (HR = 0.48, 95%CI = 0.38-0.60). Approximately 1 in 9 women who survived ≥ 1 year developed second cancer, 1 in 13 developed second non-breast cancer, and 1 in 30 developed contralateral breast cancer by 10 years. Trends in cumulative incidence declined for contralateral breast cancer but not for second non-breast cancers.

CONCLUSIONS

Elevated risks of second cancer among breast cancer survivors treated in recent decades suggests that heightened surveillance is warranted and continued efforts to reduce second cancers are needed.

The Contribution of Germline Pathogenic Variants in Breast Cancer Genes to Contralateral Breast Cancer Risk in BRCA1/BRCA2/PALB2-Negative Women

BACKGROUND

Contralateral breast cancer (CBC) is associated with younger age at first diagnosis, family history and pathogenic germline variants (PGVs) in genes such as BRCA1, BRCA2 and PALB2. However, data regarding genetic factors predisposing to CBC among younger women who are BRCA1/2/PALB2-negative remain limited.

METHODS

In this nested case-control study, participants negative for BRCA1/2/PALB2 PGVs were selected from the WECARE Study. The burden of PGVs in established breast cancer risk genes was compared in 357 cases with CBC and 366 matched controls with unilateral breast cancer (UBC). The samples were sequenced in two phases. Whole exome sequencing was used in Group 1, 162 CBC and 172 UBC (mean age at diagnosis: 42 years). A targeted panel of genes was used in Group 2, 195 CBC and 194 UBC (mean age at diagnosis: 50 years). Comparisons of PGVs burdens between CBC and UBC were made in these groups, and additional stratified sub-analysis was performed within each group according to the age at diagnosis and the time from first breast cancer (BC).

RESULTS

The PGVs burden in Group 1 was significantly higher in CBC than in UBC (p = 0.002, OR = 2.5, 95CI: 1.2-5.6), driven mainly by variants in CHEK2 and ATM. The proportions of PGVs carriers in CBC and UBC in this group were 14.8% and 5.8%, respectively. There was no significant difference in PGVs burden between CBC and UBC in Group 2 (p = 0.4, OR = 1.4, 95CI: 0.7-2.8), with proportions of carriers being 8.7% and 8.2%, respectively. There was a significant association of PGVs in CBC with younger age. Metanalysis combining both groups confirmed the significant association between the burden of PGVs and the risk of CBC (p = 0.006) with the significance driven by the younger cases (Group 1).

CONCLUSION

In younger BRCA1/BRCA2/PALB2-negative women, the aggregated burden of PGVs in breast cancer risk genes was associated with the increased risk of CBC and was inversely proportional to the age at onset.

PredictCBC-2.0: a contralateral breast cancer risk prediction model developed and validated in ~ 200,000 patients

BACKGROUND

Prediction of contralateral breast cancer (CBC) risk is challenging due to moderate performances of the known risk factors. We aimed to improve our previous risk prediction model (PredictCBC) by updated follow-up and including additional risk factors.

METHODS

We included data from 207,510 invasive breast cancer patients participating in 23 studies. In total, 8225 CBC events occurred over a median follow-up of 10.2 years. In addition to the previously included risk factors, PredictCBC-2.0 included CHEK2 c.1100delC, a 313 variant polygenic risk score (PRS-313), body mass index (BMI), and parity. Fine and Gray regression was used to fit the model. Calibration and a time-dependent area under the curve (AUC) at 5 and 10 years were assessed to determine the performance of the models. Decision curve analysis was performed to evaluate the net benefit of PredictCBC-2.0 and previous PredictCBC models.

RESULTS

The discrimination of PredictCBC-2.0 at 10 years was higher than PredictCBC with an AUC of 0.65 (95% prediction intervals (PI) 0.56-0.74) versus 0.63 (95%PI 0.54-0.71). PredictCBC-2.0 was well calibrated with an observed/expected ratio at 10 years of 0.92 (95%PI 0.34-2.54). Decision curve analysis for contralateral preventive mastectomy (CPM) showed the potential clinical utility of PredictCBC-2.0 between thresholds of 4 and 12% 10-year CBC risk for BRCA1/2 mutation carriers and non-carriers.

CONCLUSIONS

Additional genetic information beyond BRCA1/2 germline mutations improved CBC risk prediction and might help tailor clinical decision-making toward CPM or alternative preventive strategies. Identifying patients who benefit from CPM, especially in the general breast cancer population, remains challenging.

Synchronous and metachronous bilateral breast cancer among women with a history of lobular carcinoma in situ

PURPOSE

Lobular carcinoma in situ (LCIS) confers increased cancer risk in either breast, but it remains unclear if this population is at increased risk for bilateral breast cancer (BC) development. Here we report bilateral BC incidence among women with a history of LCIS.

METHODS

Women with classic-type LCIS diagnosed from 1980 to 2017 who developed unilateral BC (UBC) or bilateral BC were identified. Bilateral BC was categorized as synchronous (bilateral BC diagnosed < 6 months apart; SBBC) or metachronous (bilateral BC diagnosed ≥ 6 months apart; MBBC). Five-year incidence rates of bilateral BC among this population were evaluated. Comparisons were made to identify factors associated with bilateral BC.

RESULTS

At 7 years' median follow-up, 249/1651 (15%) women with LCIS developed BC; 34 with bilateral BC (2%). There were no clinicopathologic feature differences between those with UBC and bilateral BC. SBBC occurred in 18 without significant differences versus UBC. Among 211 with UBC and a contralateral breast at risk, 16 developed MBBC at a median follow-up of 3 years. MBBC patients were less likely to receive endocrine therapy and more likely to receive chemotherapy versus UBC. Tumor histology was not associated with MBBC. Estimated 5-year MBBC risk was 6.4%. Index estrogen/progesterone receptor positivity and endocrine therapy were the only factors associated with MBBC risk.

CONCLUSION

Bilateral BC occurred in 2% of women with LCIS history at median follow-up of 7 years. Similar to the general BC population, a decrease in MBBC is seen among women with a history of LCIS who develop hormone receptor-positive disease and those who receive endocrine therapy, highlighting the protective effects of this treatment.

Genetic, clinic and histopathologic characterization of BRCA-associated hereditary breast and ovarian cancer in southwestern Finland

We have analyzed the histopathological, clinical, and genetic characteristics in hereditary breast and ovarian cancer patients of counselled families from 1996 up to today in the southwestern Finland population. In this study we analyzed the incidence of different BRCA1 and BRCA2 pathogenic variants (PV). 1211 families were evaluated, and the families were classified as 38 BRCA1 families, 48 BRCA2 families, 689 non-BRCA families and 436 other counselled families (criteria for genetic testing was not met). In those families, the study consisted of 44 BRCA1 breast and/or ovarian cancer patients, 58 BRCA2 cancer patients, 602 non-BRCA patients and 328 other counselled patients. Breast cancer mean onset was 4.6 years earlier in BRCA1 carriers compared to BRCA2 (p = 0.07, a trend) and ovarian cancer onset almost 11 years earlier in BRCA1 families (p < 0.05). In BRCA families the onset of ovarian cancer was later than 40 years, and BRCA2-origin breast cancer was seen as late as 78 years. The BRCA PV (9%) increases the risk for same patient having both ovarian and breast cancer with a twofold risk when compared to non-BRCA group (4%) (95% CI p < 0.05). Triple-negativity in BRCA1 (42%) carriers is approximately 2.6 times vs more common than in BRCA2 carriers (16%) (p < 0.05). The risk ratio for bilateral breast cancer is approximately four times when compared BRCA2 (17%) and other counselled patients’ group (4%) (p < 0.05). 27% southwestern BRCA2-families have a unique PV, and correspondingly 39% of BRCA1-families. The results of this analysis allow improved prediction of cancer risk in high-risk hereditary breast and ovarian families in southwestern Finland and improve long term follow-up programs. According to the result it could be justified to have the discussion about prophylactic salpingo-oophorectomy by the age of 40 years. The possibility of late breast cancer onset in BRCA2 carriers supports the lifelong follow-up in BRCA carriers. Cancer onset is similar between BRCA2 carries and non-BRCA high-risk families. This study evaluated mutation profile of BRCA in southwestern Finland. In this study genotype–phenotype correlation was not found

Risk of contralateral breast cancer according to first breast cancer characteristics among women in the USA, 1992-2016

Background

Estimates of contralateral breast cancer (CBC) risk in the modern treatment era by year of diagnosis and characteristics of the first breast cancer are needed to assess the impact of recent advances in breast cancer treatment and inform clinical decision making.

Methods

We examined CBC risk among 419,818 women (age 30–84 years) who were diagnosed with a first unilateral invasive breast cancer and survived ≥ 1 year in the US Surveillance, Epidemiology, and End Results program cancer registries from 1992 to 2015 (follow-up through 2016). CBC was defined as a second invasive breast cancer in the contralateral breast ≥ 12 months after the first breast cancer. We estimated standardized incidence ratios (SIRs) of CBC by year of diagnosis, age at diagnosis, and tumor characteristics for the first breast cancer. Cumulative incidence of CBC was calculated for women diagnosed with a first breast cancer in the recent treatment era (2004–2015, follow-up through 2016).

Results

Over a median follow-up of 8 years (range 1–25 years), 12,986 breast cancer patients developed CBC. Overall, breast cancer patients had approximately twice the risk of developing cancer in the contralateral breast when compared to that expected in the general population (SIR = 2.21, 95% CI = 2.17–2.25). SIRs for CBC declined by year of first diagnosis, irrespective of age at diagnosis and estrogen receptor (ER) status (p-trends < 0.001), but the strongest decline was after an ER-positive tumor. The 5-year cumulative incidence of CBC ranged from 1.01% (95% CI = 0.90–1.14%) in younger women (age < 50 years) with a first ER-positive tumor to 1.89% (95% CI = 1.61–2.21%) in younger women with a first ER-negative tumor.

Conclusion

Declines in CBC risk are consistent with continued advances in breast cancer treatment. The updated estimates of cumulative incidence inform breast cancer patients and clinicians on the risk of CBC and may help guide treatment decisions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13058-021-01400-3.

Contralateral prophylactic mastectomy: A narrative review of the evidence and acceptability

The uptake of contralateral prophylactic mastectomy (CPM) has increased steadily over the last twenty years in women of all age groups and breast cancer stages. Since contralateral breast cancer is relatively rare and the breast cancer guidelines only recommend CPM in a small subset of patients with breast cancer, the drivers of this trend are unknown. This review aims to evaluate the evidence for and acceptability of CPM, data on patient rationales for choosing CPM, and some of the factors that might impact patient preferences. Based on the evidence, future recommendations will be provided. First, data on contralateral breast cancer risk and CPM rates and trends are addressed. After that, the evidence is structured around four main patient rationales for CPM formulated as questions that patients might ask their surgeon: Will CPM reduce mortality risk? Will CPM reduce the risk of contralateral breast cancer? Can I avoid future screening with CPM? Will I have better breast symmetry after CPM? Also, three different guidelines regarding CPM will be reviewed. Studies indicate a large gap between patient preferences for radical risk reduction with CPM and the current approaches recommended by important guidelines. We suggest a strategy including shared decision-making to enhance surgeons’ communication with patients about contralateral breast cancer and treatment options, to empower patients in order to optimize the use of CPM incorporating accurate risk assessment and individual patient preferences.

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Contralateral prophylactic mastectomy rates have increased over the last 20 years.

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Patients may want CPM to reduce risk of contralateral breast cancer and mortality.

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Patients do not always have the tools available to make a well-informed decision.

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Patient and surgeon’s shared decision-making could optimize the use of CPM.

Incidence of contralateral and ipsilateral breast cancers and prognosis in BRCA1/2 pathogenic variant carriers based on the Japanese HBOC Consortium registration

This study aimed to clarify the breast cancer prognosis in Japanese patients with BRCA1/2 pathogenic variant. We analyzed 2235 women with breast cancer who underwent BRCA1/2 genetic testing between 1996 and 2018 using data from the Japanese hereditary breast and ovarian cancer syndrome registry. The cumulative risk for contralateral and ipsilateral breast cancers and time to death since the first breast cancer were stratified based on the BRCA1/2 variant status. The median follow-up was 3.0 years (0.1-34.1 years) after the first breast cancer. The annual average risks of contralateral breast cancer in BRCA1 and BRCA2 and non-BRCA1/2 pathogenic variant carriers were 4.0%, 2.9%, and 1.9%, respectively (P = 0.001). The annual average risks of ipsilateral breast cancer in the three groups were 2.7%, 1.4%, and 1.1%, respectively (P = 0.06). BRCA1 pathogenic variant carriers had significantly higher risks of contralateral (hazard ratio 1.91, P < 0.001) and ipsilateral (hazard ratio 2.00, P = 0.02) breast cancers than non-BRCA1/2 pathogenic variant carriers. The time to death by the BRCA1/2 variant status was not significantly difference (P = 0.28). The prognosis of breast cancer patients who received standard treatment was comparable regardless of the BRCA1/2 variant status.

Autologous Unilateral Breast Reconstruction with Venous Supercharged IMAP-Flaps: A Step by Step Guide of the Split Breast Technique

Various techniques for breast reconstruction ranging from reconstruction with implants to free tissue transfer, with the disadvantage of either carrying a foreign body or dealing with donor site morbidity, have been described. In patients who had a unilateral mastectomy and offer a contralateral mamma hypertrophy a breast reconstruction can be performed with the excess tissue from the hypertrophic side using the split breast technique. Here a local internal mammary artery perforator (IMAP) flap of the hypertrophic breast can be used for reconstruction avoiding the downsides of implants or a microsurgical reconstruction and simultaneously reducing the enlarged donor breast in order to achieve symmetry. Methods: Between April 2010 and February 2019 the split breast technique was performed in five patients after mastectomy due to breast cancer. Operating time, length of stay, complications and the need for secondary operations were analyzed and the surgical technique including flap supercharging were described in detail. Results: All five IMAP-flaps survived and an aesthetically pleasant result could be achieved using the split breast technique. An average of two secondary corrections to achieve better symmetry were necessary after each breast reconstruction. Complications included venous flap congestion, partial flap necrosis and asymmetry. No breast cancer recurrence was recorded. An overall approval of the surgical technique among patients was observed. Conclusions: The use of the contralateral breast for unilateral total breast reconstruction represents an additional highly useful technique for selected patients, is safe and reliable results can be achieved. Although this technique is carried out as a single-stage procedure, including breast reduction and reconstruction at the same time, secondary operations may be necessary to achieve superior symmetry and a satisfying aesthetic result. Survival of the IMAP-flaps can be improved by venous supercharging of the flaps onto the thoracoepigastric vein.

The Influence of Adjuvant Systemic Regimens on Contralateral Breast Cancer Risk and Receptor Subtype

BACKGROUND

An increasing number of breast cancer (BC) survivors are at risk of developing contralateral breast cancer (CBC). We aimed to investigate the influence of various adjuvant systemic regimens on, subtype-specific, risk of CBC.

METHODS

This population-based cohort study included female patients diagnosed with first invasive BC between 2003 and 2010; follow-up was complete until 2016. Clinico-pathological data were obtained from the Netherlands Cancer Registry and additional data on receptor status through linkage with PALGA: the Dutch Pathology Registry. Cumulative incidences (death and distant metastases as competing risk) and hazard ratios (HRs) were estimated for all invasive metachronous CBC and CBC subtypes.

RESULTS

Of 83 144 BC patients, 2816 developed a CBC; the 10-year cumulative incidence was 3.8% (95% confidence interval [CI] = 3.7% to 4.0%). Overall, adjuvant chemotherapy (HR = 0.70, 95% CI = 0.62 to 0.80), endocrine therapy (HR = 0.46, 95% CI = 0.41 to 0.52), and trastuzumab with chemotherapy (HR = 0.57, 95% CI = 0.45 to 0.73) were strongly associated with a reduced CBC risk. Specifically, taxane-containing chemotherapy (HR = 0.48, 95% CI = 0.36 to 0.62) and aromatase inhibitors (HR = 0.32, 95% CI = 0.23 to 0.44) were associated with a large CBC risk reduction. More detailed analyses showed that endocrine therapy statistically significantly decreased the risk of estrogen receptor (ER)-positive CBC (HR = 0.41, 95% CI = 0.36 to 0.47) but not ER-negative CBC (HR = 1.32, 95% CI = 0.90 to 1.93) compared with no endocrine therapy. Patients receiving chemotherapy for ER-negative first BC had a higher risk of ER-negative CBC from 5 years of follow-up (HR = 2.84, 95% CI = 1.62 to 4.99) compared with patients not receiving chemotherapy for ER-negative first BC.

CONCLUSION

Endocrine therapy, chemotherapy, as well as trastuzumab with chemotherapy reduce CBC risk. However, each adjuvant therapy regimen had a different impact on the CBC subtype distribution. Taxane-containing chemotherapy and aromatase inhibitors were associated with the largest CBC risk reduction.

Prediction and clinical utility of a contralateral breast cancer risk model

BACKGROUND

Breast cancer survivors are at risk for contralateral breast cancer (CBC), with the consequent burden of further treatment and potentially less favorable prognosis. We aimed to develop and validate a CBC risk prediction model and evaluate its applicability for clinical decision-making.

METHODS

We included data of 132,756 invasive non-metastatic breast cancer patients from 20 studies with 4682 CBC events and a median follow-up of 8.8 years. We developed a multivariable Fine and Gray prediction model (PredictCBC-1A) including patient, primary tumor, and treatment characteristics and BRCA1/2 germline mutation status, accounting for the competing risks of death and distant metastasis. We also developed a model without BRCA1/2 mutation status (PredictCBC-1B) since this information was available for only 6% of patients and is routinely unavailable in the general breast cancer population. Prediction performance was evaluated using calibration and discrimination, calculated by a time-dependent area under the curve (AUC) at 5 and 10 years after diagnosis of primary breast cancer, and an internal-external cross-validation procedure. Decision curve analysis was performed to evaluate the net benefit of the model to quantify clinical utility.

RESULTS

In the multivariable model, BRCA1/2 germline mutation status, family history, and systemic adjuvant treatment showed the strongest associations with CBC risk. The AUC of PredictCBC-1A was 0.63 (95% prediction interval (PI) at 5 years, 0.52-0.74; at 10 years, 0.53-0.72). Calibration-in-the-large was -0.13 (95% PI: -1.62-1.37), and the calibration slope was 0.90 (95% PI: 0.73-1.08). The AUC of Predict-1B at 10 years was 0.59 (95% PI: 0.52-0.66); calibration was slightly lower. Decision curve analysis for preventive contralateral mastectomy showed potential clinical utility of PredictCBC-1A between thresholds of 4-10% 10-year CBC risk for BRCA1/2 mutation carriers and non-carriers.

CONCLUSIONS

We developed a reasonably calibrated model to predict the risk of CBC in women of European-descent; however, prediction accuracy was moderate. Our model shows potential for improved risk counseling, but decision-making regarding contralateral preventive mastectomy, especially in the general breast cancer population where limited information of the mutation status in BRCA1/2 is available, remains challenging.

Preventive drug therapy and contralateral breast cancer: summary of the evidence of clinical trials and observational studies

Background: Breast cancer patients have a lifelong 2-4-fold increased risk of developing a second primary tumor in the contralateral breast compared with the risk for a first primary breast cancer in the general female population. Prevention of contralateral breast cancer (CBC) has received increased attention during recent decades. Here, we summarize and discuss the available literature on drug preventive therapy and CBC.Results: The endocrine-targetting drugs, tamoxifen and aromatase inhibitors are used as standard adjuvant treatment for estrogen receptor (ER)-positive breast cancer. Both are associated with relative risk reductions of CBC of up to 50%, but incur serious side effects. Several prescription drugs originally developed for other purposes, including bisphosphonates, statins, non-steroidal anti-inflammatory drugs, metformin, anti-hypertensives and retinoids, have shown anti-cancer activity in preclinical models. However, results of observational studies on CBC are sparse and inconsistent, with only statins demonstrating promise as preventive agents and a potential treatment option for ER-negative breast cancer patients.Conclusion: Future studies are needed to assess the effect of statins in risk reduction and to identify other drugs with chemopreventive potential against CBC. Eventually, efforts must be directed towards identifying those breast cancer patients likely to benefit most from specific preventive therapies.

CYP2D6 phenotype, tamoxifen, and risk of contralateral breast cancer in the WECARE Study

BACKGROUND

Tamoxifen treatment greatly reduces a woman's risk of developing a second primary breast cancer. There is, however, substantial variability in treatment response, some of which may be attributed to germline genetic variation. CYP2D6 is a key enzyme in the metabolism of tamoxifen to its active metabolites, and variants in this gene have been associated with reduced tamoxifen metabolism. The impact of variation on risk of contralateral breast cancer (CBC) is unknown.

METHODS

Germline DNA from 1514 CBC cases and 2203 unilateral breast cancer controls was genotyped for seven single nucleotide polymorphisms, one three-nucleotide insertion-deletion, and a full gene deletion. Each variant has an expected impact on enzyme activity, which in combination allows for the classification of women as extensive, intermediate, and poor metabolizers (EM, IM, and PM respectively). Each woman was assigned one of six possible diplotypes and a corresponding CYP2D6 activity score (AS): EM/EM (AS = 2), EM/IM (AS = 1.5), EM/PM (AS = 1), IM/IM (AS = 0.75), IM/PM (AS = 0.5), and PM/PM (AS = 0). We also collapsed categories of the AS to generate an overall phenotype (EM, AS ≥ 1; IM, AS = 0.5-0.75; PM, AS = 0). Rate ratios (RRs) and 95% confidence intervals (CIs) for the association between tamoxifen treatment and risk of CBC in our study population were estimated using conditional logistic regression, stratified by AS.

RESULTS

Among women with AS ≥ 1 (i.e., EM), tamoxifen treatment was associated with a 20-55% reduced RR of CBC (AS = 2, RR = - 0.81, 95% CI 0.62-1.06; AS = 1.5, RR = 0.45, 95% CI 0.30-0.68; and AS = 1, RR = 0.55, 95% CI 0.40-0.74). Among women with no EM alleles and at least one PM allele (i.e., IM and PM), tamoxifen did not appear to impact the RR of CBC in this population (AS = 0.5, RR = 1.08, 95% CI 0.59-1.96; and AS = 0, RR = 1.17, 95% CI 0.58-2.35) (p for homogeneity = - 0.02).

CONCLUSION

This study suggests that the CYP2D6 phenotype may contribute to some of the observed variability in the impact of tamoxifen treatment for a first breast cancer on risk of developing CBC.

Risk factors for metachronous contralateral breast cancer: A systematic review and meta-analysis

BACKGROUND

The risk of developing metachronous contralateral breast cancer (CBC) is a recurrent topic at the outpatient clinic. We aimed to provide CBC risk estimates of published patient, pathological, and primary breast cancer (PBC) treatment-related factors.

METHODS

PubMed was searched for publications on factors associated with CBC risk. Meta-analyses were performed with grouping of studies by mutation status (i.e., BRCA1, BRCA2, CHEK2 c.1100delC), familial cohorts, and general population-based cohorts.

RESULTS

Sixty-eight papers satisfied our inclusion criteria. Strong associations with CBC were found for carrying a BRCA1 (RR = 3.7; 95%CI:2.8-4.9), BRCA2 (RR = 2.8; 95%CI:1.8-4.3) or CHEK2 c.1100delC (RR = 2.7; 95%CI:2.0-3.7) mutation. In population-based cohorts, PBC family history (RR = 1.8; 95%CI:1.2-2.6), body mass index (BMI) ≥30 kg/m² (RR = 1.5; 95%CI:1.3-1.9), lobular PBC (RR = 1.4; 95%CI:1.1-1.8), estrogen receptor-negative PBC (RR = 1.5; 95%CI:1.0-2.3) and treatment with radiotherapy <40 years (RR = 1.4; 95%CI:1.1-1.7) was associated with increased CBC risk. Older age at PBC diagnosis (RR per decade = 0.93; 95%CI:0.88-0.98), and treatment with chemotherapy (RR = 0.7; 95%CI:0.6-0.8) or endocrine therapy (RR = 0.6; 95%CI:0.5-0.7) were associated with decreased CBC risk.

CONCLUSIONS

Mutation status, family history, and PBC treatment are key factors for CBC risk. Age at PBC diagnosis, BMI, lobular histology and hormone receptor status have weaker associations and should be considered in combination with key factors to accurately predict CBC risk.

PI3K/Akt/mTOR signalling pathway activation in patients with ER-positive, metachronous, contralateral breast cancer treated with hormone therapy

Oestrogen receptor (ER)-positive, metachronous, contralateral breast cancer (MCBC) sometimes develops during or soon after completion of hormone therapy (HT), but it is uncertain whether it is HT-resistant. We examined the association between ER-positive second cancer and activation of the phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) and mitogen-activated protein kinase (MAPK) pathways, which are associated with HT resistance. We examined the treatment-free interval (time after completion of HT for initial cancer) in 41 patients with ER-positive MCBC with a history of adjuvant HT for initial cancer (HT group), and initial-to-second period duration (time after operation of initial cancer to onset of second cancer) in 17 patients with ER-positive MCBC in whom adjuvant HT was not applied to the initial tumour (control group or no HT group). Phosphorylated S6 (pS6) and phosphorylated MAPK (pMAPK) were used as indicators of PI3K/Akt/mTOR and MAPK pathway activity, respectively. Tumours were classified as showing negative, positive or strongly positive staining, and the correlation between staining and treatment-free interval or initial-to-second period duration was evaluated using the Spearman's rank correlation coefficient (ρ). Treatment-free interval and pS6 staining showed a negative correlation (ρ=-0.5355; P=0.0003) in the HT group. There was no correlation between initial-to-second period duration and pS6 staining in the no HT group (ρ=-0.0814; P=0.756). There was no correlation between pMAPK signalling and the treatment-free interval in the HT group (ρ=-0.1560; P=0.330) or the initial-to-second period duration in the no HT group (ρ=-0.0116; P=0.965). Development of a second ER-positive cancer during or soon after completion of HT for the initial cancer may be associated with activation of the PI3K/Akt/mTOR pathway. Care should be taken during follow-up and when selecting adjuvant therapy for second cancer.

Tumour characteristics of bilateral screen-detected cancers and bilateral interval cancers in women participating at biennial screening mammography

BACKGROUND

Unilateral interval breast cancers show less favourable prognostic features than unilateral screen-detected cancers, but data on tumour characteristics of bilateral interval cancers in a systematically screened population are sparse. Therefore, we compared tumour characteristics of bilateral interval cancers with those of bilateral screen-detected cancers.

METHODS

We included all 468,720 screening mammograms of women who underwent biennial screening mammography in the South of the Netherlands between January 2005 and January 2015. We collected breast imaging reports, biopsy results and surgical reports of all recalled women and of all women who presented with interval breast cancer. In women with synchronous bilateral breast cancer, the tumour with the highest tumour stage was defined as the index cancer. For comparison of data between both groups Fisher exact test and Chi-square test were used.

RESULTS

Synchronous bilateral cancer was diagnosed in 2.2% of screen-detected cancers (64/2947) and in 3.2% of interval cancers (24/753) (P = 0.1). Index tumours of bilateral screen-detected cancers and interval cancers showed similar characteristics, except for a larger proportion of T-stage 2 or worse (T2+) cancers among interval cancers (16/24 (66.7%) versus 23/58 (39.7%) (P = 0.03). Index cancers, compared to contralateral cancers, were less frequently stage T1 in both bilateral screen-detected cancers and bilateral interval cancers (35/64 (60.3%) versus 40/64 (88.9%) (P = 0.001) and 8/24 (33.3%) versus 18/24 (85.7%) (P < 0.001), respectively). In bilateral screen-detected cancers, contralateral cancers were more often stage 1a-c (P < 0.001) compared to index cancers. In bilateral index cancers, index cancers were more often of the lobular subtype (P < 0.001).

CONCLUSION

Index cancers of bilateral screen-detected cancers and bilateral interval cancers show significant differences in tumour size, whereas nodal status, receptor status and final surgical treatment are comparable. In bilateral screen-detected cancer, index cancers had a significantly higher tumour stage. In bilateral screen-detected cancer, index cancers were more often the ductal invasive subtype compared to contralateral cancers.

Low-dose aspirin use and risk of contralateral breast cancer: a Danish nationwide cohort study

Observational studies of aspirin use and breast cancer risk have provided inconsistent results. The occurrence of contralateral breast cancer (CBC) among breast cancer survivors may serve as a useful high-risk model to identify preventive drug effects. Using this model, we examined the association between post-diagnosis use of low-dose aspirin and risk of CBC. We identified all women recorded with a first primary breast cancer in the Danish Breast Cancer Cooperative Group Database between 1996 and 2012. Information on drug use, tumor and patient characteristics, treatment, and CBC was obtained from nationwide registries. In the main analysis, we defined time-varying post-diagnosis low-dose aspirin use as two or more prescriptions filled during follow-up and applied a one-year exposure lag. Cox proportional hazard regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between post-diagnosis low-dose aspirin use and CBC risk. Among 52,723 breast cancer patients, 1,444 women developed CBC during a median follow-up of 4.8 years. The adjusted HR for CBC associated with post-diagnosis use of low-dose aspirin was 0.91 (95% CI: 0.75-1.09). We observed no substantial variation in HRs according to pattern of low-dose aspirin use or estrogen receptor status of the first or the contralateral breast cancer. In conclusion, this large nationwide cohort study of breast cancer survivors does not provide strong evidence suggesting an association between post-diagnosis use of low-dose aspirin and risk of CBC.

Dose-dependent effect of mammographic breast density on the risk of contralateral breast cancer

PURPOSE

Increased mammographic breast density is a significant risk factor for breast cancer. It is not clear if it is also a risk factor for the development of contralateral breast cancer.

METHODS

The data were obtained from Breast Cancer Surveillance Consortium and included women diagnosed with invasive breast cancer or ductal carcinoma in situ between ages 18 and 88 and years 1995 and 2009. Each case of contralateral breast cancer was matched with three controls based on year of first breast cancer diagnosis, race, and length of follow-up. A total of 847 cases and 2541 controls were included. The risk factors included in the study were mammographic breast density, age of first breast cancer diagnosis, family history of breast cancer, anti-estrogen treatment, hormone replacement therapy, menopausal status, and estrogen receptor status, all from the time of first breast cancer diagnosis. Both univariate analysis and multivariate conditional logistic regression analysis were performed.

RESULTS

In the final multivariate model, breast density, family history of breast cancer, and anti-estrogen treatment remained significant with p values less than 0.01. Increasing breast density had a dose-dependent effect on the risk of contralateral breast cancer. Relative to 'almost entirely fat' category of breast density, the adjusted odds ratios (and p values) in the multivariate analysis for 'scattered density,' 'heterogeneously dense,' and 'extremely dense' categories were 1.65 (0.036), 2.10 (0.002), and 2.32 (0.001), respectively.

CONCLUSION

Breast density is an independent and significant risk factor for development of contralateral breast cancer. This risk factor should contribute to clinical decision making.

Mortality after contralateral breast cancer in Denmark

PURPOSE

How a second breast cancer diagnosis affects survival in comparison with unilateral breast cancer (UBC) is unclear. Prognostic factors for contralateral breast cancer (CBC) are also not well established. We aimed to investigate the survival pattern after CBC with particular focus on time between first and second breast cancer diagnosis and age at CBC diagnosis.

METHODS

Within the nationwide Danish Breast Cancer Cooperative Group database, we identified 68,466 breast cancer patients diagnosed during 1978-2012. Patients who subsequently developed CBC were identified in a previously established database (N = 3004). Patients were followed for breast cancer-specific death in the Danish Register of Causes of Death until 2015. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazard regression models. Cumulative breast cancer mortality from date of CBC was estimated using the Aalen-Johansen method.

RESULTS

Compared with UBC patients, the rate of dying from breast cancer was more than twofold higher following a CBC diagnosis, after adjustment for age, period, tumor characteristics, and treatment of the first breast cancer (HR 2.48; 95% CI 2.31-2.66). Short time interval (< 5 years) was associated with higher breast cancer-specific mortality after CBC among patients < 70 years at CBC diagnosis compared with longer time intervals, but not among patients ≥ 70 years at CBC diagnosis.

CONCLUSION

Breast cancer-specific mortality rates were markedly higher after compared with before a CBC diagnosis. We found higher breast cancer-specific mortality after CBC associated with a short interval between diagnoses among patients diagnosed with CBC before age 70 years.

Development and pilot testing of a Decision Aid (DA) for women with early-stage breast cancer considering contralateral prophylactic mastectomy

OBJECTIVE

Describe the development, acceptability and feasibility of a Decision Aid (DA) for women with early-stage breast cancer (BC) at average contralateral breast cancer (CBC) risk considering contralateral prophylactic mastectomy (CPM).

METHODS

The DA was developed using the International Patient Decision Aid Standards (IPDAS) and the Ottawa Decision Support Framework. It provides evidence-based information about CPM in a booklet format combining text, graphs and images of surgical options. Twenty-three women with a history of early-stage breast cancer were interviewed in person or over the phone using a 'think aloud approach'. Framework analysis was used to code and analyse data.

RESULTS

Twenty-three women participated in the study. Mean age of participants was 58.6 years and time since diagnosis ranged from 14 months to 21 years. Five women had CPM and eighteen had not. Women strongly endorsed the DA. Many felt validated by a section on appearance and found information on average risk of recurrence and metastases helpful, however, noted the importance of discussing personal risk with their surgeon. Many requested more information on surgery details (time taken, recovery) and costs of the different options.

CONCLUSION

The DA was acceptable to women, including the format, content and proposed implementation strategies. Practical and financial issues are important to women in considering treatment options.

PRACTICE IMPLICATIONS

Women appreciate information about CPM at diagnosis and emphasised the importance of discussing potential downsides of the procedure in addition to benefits. The DA was considered acceptable to facilitate such discussions.

Frequency and characteristics of contralateral breast abnormalities following recall at screening mammography

PURPOSE

To determine the frequency and characteristics of contralateral, non-recalled breast abnormalities following recall at screening mammography.

METHODS

We included a series of 130,338 screening mammograms performed between 1 January 2014 and 1 January 2016. During the 1-year follow-up, clinical data were collected for all recalls. Screening outcome was determined for recalled women with or without evaluation of contralateral breast abnormalities.

RESULTS

Of 3,995 recalls (recall rate 3.1%), 129 women (3.2%) underwent assessment of a contralateral, non-recalled breast abnormality. Most lesions were detected at clinical mammography and/or breast tomosynthesis (101 women, 78.3%). The biopsy rate was similar for recalled lesions and contralateral, non-recalled lesions, but the positive predictive value of biopsy was higher for recalled lesions (p = 0.01). A comparable proportion of the recalled lesions and contralateral, non-recalled lesions were malignant (p = 0.1). The proportion of ductal carcinoma in situ was similar for both groups, as well as invasive cancer characteristics and type of surgical treatment.

CONCLUSIONS

About 3% of recalled women underwent evaluation of contralateral, non-recalled breast lesions. Evaluation of the contralateral breast after recall is important as we found that 15.5% of contralateral, non-recalled lesions were malignant. Contralateral cancers and screen-detected cancers show similar characteristics, stage and surgical treatment.

KEY POINTS

• 3% of recalled women underwent evaluation of contralateral, non-recalled lesions • One out of seven contralateral, non-recalled lesions was malignant • A contralateral cancer was diagnosed in 0.5% of recalls • Screen-detected cancers and non-recalled, contralateral cancers showed similar histological characteristics • Tumour stage and surgical treatment were similar for both groups.

Incidence of isolated local breast cancer recurrence and contralateral breast cancer: A systematic review

An increasing number of women is surviving breast cancer and due to that at risk of developing an isolated ipsilateral breast tumor recurrence (IBTR) or a contralateral breast cancer (CBC). Patients' main concern is cancer recurrence. Patient counseling on breast cancer recurrence is challenging. In order to provide healthcare professionals and patients more guidance, a systematic literature review of the incidence of isolated IBTR and CBC in women diagnosed with early invasive breast cancer was performed. Medline, EMBASE and the Cochrane Library were searched from 2000 until October 2015. Multicenter studies reporting an IBTR or CBC rate in curatively treated adult females diagnosed with invasive breast cancer were included. The initial search yielded 6998 potentially relevant articles. Twenty were eligible for inclusion, representing 25 recurrence incidence rates. Both isolated IBTR and CBC incidence rates steadily increased with the length of follow-up, indicating that IBTR and CBC occur even more than 15 years after diagnosis. The annual incidence rate of isolated IBTR and CBC in women diagnosed with an early invasive breast cancer was 0.6% (range: 0.4-1.1%) and 0.5% (range: 0.2-0.7%), respectively. Analyzed data were lacking information about important risk factors and given treatment with regard to the incidence of recurrence, which hampers the prediction of patient tailored recurrence risks. The presented rates are therefore the best available estimates of isolated IBTR and CBC annual incidence rates based on the current literature. Healthcare professionals could use these rates in their communication with patients diagnosed with early invasive breast cancer.

Low Lifetime Risk of Contralateral Breast Cancer in a Middle-Income Asian Country: Evidence to Guide Post-treatment Surveillance

BACKGROUND

The rate of contralateral risk-reducing mastectomy (CRRM) is increasing in the West with controversial evidence of improved survival in early breast cancer patients. Although uptake of CRRM in Asia appears low, the trends may rise, and there is currently an urgent need to provide evidence for informed decision-making in clinical practice. This study aims to determine the risk of contralateral breast cancer (CBC) and its associated factors in an Asian setting.

METHOD

A total of 2937 newly diagnosed patients with stage I and stage II breast cancer in University Malaya Medical Centre between Jan 1993 to Dec 2012 were included in the study. Multinomial logistic regression analysis allowing death to compete with CBC as a study outcome was used; patients with unilateral breast cancer who were alive were taken as reference. A stepwise backward regression analysis including age at diagnosis, ethnicity, family history of breast cancer, TNM stage, hormonal receptor status, HER2 status, chemotherapy, radiotherapy, and hormone therapy was conducted.

RESULTS

Fifty women developed CBC, over a median follow-up of 6 years. The 5- and 10-year cumulative risk of contralateral breast cancer was 1.0% (95% CI 0.6-1.4%) and 2.8% (95% CI 2.0-3.6%), respectively. Young age at diagnosis of first cancer, positive family history, and stage I disease were independent predictors of CBC.

DISCUSSION

The current study suggests that the risk of CBC is very low in a Southeast Asian setting. Any recommendations or practice of CRRM should be reviewed with caution and patients must be counseled appropriately.

Natural History of Invasive Papillary Breast Carcinoma Followed for 10 Years: A Case Report and Literature Review

Diachronic research on untreated breast cancer completely depends on past medical records when no more recent, advanced methods are available. Herein, we report a case of invasive papillary breast carcinoma followed for 10 years in a 59-year-old woman who refused any treatment. The diagnosis was based on core needle biopsies. At the patient's first visit in July 2006, the tumor measured 10.4 × 7.2 × 3.5 cm. It was staged as IIIB (T4bN1). In May 2016, the tumor was staged as IIIC (T4bN3a). In the past 10 years, the tumor has increased to 12.1 × 9.0 × 4.2 cm. However, a whole-body bone scan and ¹⁸F-FDG PET/CT showed no evidence of distant metastasis. Immunohistochemistry results, corresponding to biopsies taken at subsequent examinations, have remained unaltered since 2006. The tumor was estrogen/progesterone receptor-positive and C-erbB2 expression was not detected. The Ki-67 labeling index was around 10%.

Breast MRI increases the number of mastectomies for ductal cancers, but decreases them for lobular cancers

PURPOSE

In this retrospective population-based cohort study, we analyzed breast MRI use and its impact on type of surgery, surgical margin involvement, and the diagnosis of contralateral breast cancer.

METHODS

All Dutch patients with cT_1-4N_0-3M₀ breast cancer diagnosed in 2011-2013 and treated with primary surgery were eligible for inclusion. Using multivariable analyses, we analyzed in different categories whether MRI use was related to surgery type, margin involvement, and diagnosis of contralateral breast cancer (CBC).

RESULTS

MRI was performed in 10,740 out of 36,050 patients (29.8%). Patients with invasive ductal cancer undergoing MRI were more likely to undergo primary mastectomy than those without MRI (OR 1.30, 95% confidence interval (CI) 1.22-1.39, p < 0.0001). Patients with invasive lobular cancer undergoing MRI were less likely to undergo primary mastectomy than those without MRI (OR 0.86, 95% CI 0.76-0.99, p = 0.0303). A significantly lower risk of positive surgical margins after breast-conserving surgery was only seen in patients with lobular cancer who had undergone MRI as compared to those without MRI (OR 0.59, 95% CI 0.44-0.79, p = 0.0003) and, consequently, a lower risk of secondary mastectomy (OR 0.61, 95% CI 0.42-0.88, p = 0.0088). Patients who underwent MRI were almost four times more likely to be diagnosed with CBC (OR 3.55, 95% CI 3.01-4.17, p < 0.0001).

CONCLUSIONS

Breast MRI use was associated with a reduced number of mastectomies and less positive surgical margins in invasive lobular cancer, but with an increased number of mastectomies in ductal cancers. Breast MRI use was associated with a fourfold higher incidence of CBC.

A model for individualized risk prediction of contralateral breast cancer

PURPOSE

Patients diagnosed with invasive breast cancer (BC) or ductal carcinoma in situ are increasingly choosing to undergo contralateral prophylactic mastectomy (CPM) to reduce their risk of contralateral BC (CBC). This is a particularly disturbing trend as a large proportion of these CPMs are believed to be medically unnecessary. Many BC patients tend to substantially overestimate their CBC risk. Thus, there is a pressing need to educate patients effectively on their CBC risk. We develop a CBC risk prediction model to aid physicians in this task.

METHODS

We used data from two sources: Breast Cancer Surveillance Consortium and Surveillance, Epidemiology, and End Results to build the model. The model building steps are similar to those used in developing the BC risk assessment tool (popularly known as Gail model) for counseling women on their BC risk. Our model, named CBCRisk, is exclusively designed for counseling women diagnosed with unilateral BC on the risk of developing CBC.

RESULTS

We identified eight factors to be significantly associated with CBC-age at first BC diagnosis, anti-estrogen therapy, family history of BC, high-risk pre-neoplasia status, estrogen receptor status, breast density, type of first BC, and age at first birth. Combining the relative risk estimates with the relevant hazard rates, CBCRisk projects absolute risk of developing CBC over a given period.

CONCLUSIONS

By providing individualized CBC risk estimates, CBCRisk may help in counseling of BC patients. In turn, this may potentially help alleviate the rate of medically unnecessary CPMs.

Association of Adjuvant Tamoxifen and Aromatase Inhibitor Therapy With Contralateral Breast Cancer Risk Among US Women With Breast Cancer in a General Community Setting

Importance

Within 10 years after breast cancer diagnosis, roughly 5% of patients develop contralateral breast cancer (CBC). Randomized trials have found that therapy including tamoxifen citrate and aromatase inhibitors (AIs) reduces CBC risk. But little is known about the magnitude and duration of protective associations within the context of real-world clinical management settings, where varying durations of and gaps in treatment are common.

Objective

To determine the association between adjuvant tamoxifen and AI therapy and CBC risk within a general community setting.

Design, Setting, and Participants

A retrospective cohort study of CBC risk among 7541 patients diagnosed with a first primary unilateral invasive breast cancer at Kaiser Permanente Institute for Health Research (Colorado) or Kaiser Permanente Northwest Center for Health Research (Oregon) between January 1, 1990, and December 31, 2008. Data were analyzed from 1 year after diagnosis of the first breast cancer through the earliest of the following events: CBC diagnosis, other second cancer diagnosis, death, last tumor registry follow-up, exit from the Kaiser Permanente health care plan, or end of study follow-up (December 31, 2010, for Oregon and December 31, 2011, for Colorado).

Exposures

Adjuvant tamoxifen use and AI therapy were treated as time-dependent exposures, assessed using electronic prescription records.

Main Outcomes and Measures

Incident CBC based on long-term systematic follow-up.

Results

Among 7541 women with invasive breast cancer, median age at initial breast cancer diagnosis was 60.6 years (age range, 24.9-84.9 years). Women were predominantly (92.9% [7009 of 7541]) of white race. During a median of 6.3 years (range, 1-20.9 years) of follow-up, 248 women developed CBC (45 in situ and 203 invasive). Contralateral breast cancer risk decreased significantly with increasing tamoxifen therapy duration. In current users, the relative risk (RR) per year of tamoxifen use was 0.76 (95% CI, 0.64-0.89), with an estimated 66% (RR, 0.34; 95% CI, 0.29-0.40) RR reduction for 4 years of use compared with nonusers. Risk reductions were slightly smaller for past users but were still significant at least 5 years after stopping tamoxifen therapy (RR per year of use, 0.85; 95% CI, 0.71-0.995). In addition, AI use without tamoxifen therapy was associated with reduced CBC risk (RR for AI users compared with nonusers, 0.48; 95% CI, 0.22-0.97). Risk reductions were most apparent among women whose primary and CBCs were estrogen receptor positive.

Conclusions and Relevance

Tamoxifen therapy was associated with reduced CBC risk during treatment and after its cessation, with risk progressively decreasing as tamoxifen therapy duration increased. Among those surviving at least 5 years, tamoxifen use for at least 4 years was estimated to prevent 3 CBCs per 100 women by 10 years after an estrogen receptor-positive first breast cancer, an absolute risk reduction that is consistent with findings from clinical trials. If adjuvant endocrine therapy is indicated for breast cancer treatment, these findings in concert with trial data suggest that women should be encouraged to complete the full course.

Body mass index, weight change, and risk of second primary breast cancer in the WECARE study: influence of estrogen receptor status of the first breast cancer

Studies examining the relationship between body mass index (BMI) and risk of contralateral breast cancer (CBC) have reported mixed findings. We previously showed that obese postmenopausal women with estrogen receptor (ER)‐negative breast cancer have a fivefold higher risk of CBC compared with normal weight women. In the current analysis, we reexamined this relationship in the expanded Women's Environmental Cancer and Radiation Epidemiology (WECARE) Study, focusing on the impact of menopausal status and ER status of the first breast cancer. The WECARE Study is a population‐based case–control study of young women with CBC (cases, N = 1386) and with unilateral breast cancer (controls, N = 2045). Rate ratios (RR) and 95% confidence intervals (CI) were calculated to assess the relationship between BMI and risk of CBC stratified by menopausal and ER status. Positive associations with obesity and weight gain were limited to women who became postmenopausal following their first primary breast cancer. Among those with an ER‐negative first breast cancer, obesity (vs. normal weight) at first diagnosis was associated with an increased risk of CBC (RR = 1.9, 95% CI: 1.02, 3.4). Also, weight gain of ≥10 kg after first diagnosis was associated with an almost twofold increased risk of CBC (RR = 1.9, 95% CI: 0.99, 3.8). These results suggest that women with an ER‐negative first primary cancer who are obese at first primary diagnosis or who experience a large weight gain afterward may benefit from heightened surveillance. Future studies are needed to address the impact of weight loss interventions on risk of CBC.

Feasibility of reusing time-matched controls in an overlapping cohort

The methods developed for secondary analysis of nested case-control data have been illustrated only in simplified settings in a common cohort and have not found their way into biostatistical practice. This paper demonstrates the feasibility of reusing prior nested case-control data in a realistic setting where a new outcome is available in an overlapping cohort where no new controls were gathered and where all data have been anonymised. Using basic information about the background cohort and sampling criteria, the new cases and prior data are "aligned" to identify the common underlying study base. With this study base, a Kaplan-Meier table of the prior outcome extracts the risk sets required to calculate the weights to assign to the controls to remove the sampling bias. A weighted Cox regression, implemented in standard statistical software, provides unbiased hazard ratios. Using the method to compare cases of contralateral breast cancer to available controls from a prior study of metastases, we identified a multifocal tumor as a risk factor that has not been reported previously. We examine the sensitivity of the method to an imperfect weighting scheme and discuss its merits and pitfalls to provide guidance for its use in medical research studies.

Systemic therapy for breast cancer and risk of subsequent contralateral breast cancer in the WECARE Study

Background

Treatment with tamoxifen or chemotherapy reduces the risk of contralateral breast cancer (CBC). However, it is uncertain how long the protection lasts and whether the protective effect is modified by patient, tumor, or treatment characteristics.

Methods

The population-based WECARE Study included 1521 cases with CBC and 2212 age- and year of first diagnosis-matched controls with unilateral breast cancer recruited during two phases in the USA, Canada, and Denmark. Women were diagnosed with a first breast cancer before age 55 years during 1985–2008. Abstraction of medical records provided detailed treatment information, while information on risk factors was obtained during telephone interviews. Risk ratios (RRs) and 95 % confidence intervals (CIs) for CBC were obtained from multivariable conditional logistic regression models.

Results

Compared with never users of tamoxifen, the RR of CBC was lower for current users of tamoxifen (RR = 0.73; 95 % CI = 0.55–0.97) and for past users within 3 years of last use (RR = 0.73; 95 % CI = 0.53–1.00). There was no evidence of an increased risk of estrogen receptor-negative CBC associated with ever use of tamoxifen or use for 4.5 or more years. Use of chemotherapy (ever versus never use) was associated with a significantly reduced RR of developing CBC 1–4 years (RR = 0.59; 95 % CI = 0.45–0.77) and 5–9 years (RR = 0.73; 95 % CI = 0.56–0.95) after first breast cancer diagnosis. RRs of CBC associated with tamoxifen or with chemotherapy use were independent of age, family history of breast cancer, body mass index and tumor characteristics of the first breast cancer with the exception that the RR of CBC was lower for lobular histology compared with other histologies.

Conclusion

Our findings are consistent with previous studies showing that treatment with tamoxifen or chemotherapy is associated with a lower risk of CBC although the risk reduction appears to last for a limited time period after treatment is completed.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-016-0726-0) contains supplementary material, which is available to authorized users.

Effectiveness of Prophylactic Surgeries in BRCA1 or BRCA2 Mutation Carriers: A Meta-analysis and Systematic Review

PURPOSE

To systematically investigate the effectiveness of prophylactic surgeries (PS) implemented in women carrying BRCA1/2 mutations.

EXPERIMENTAL DESIGN

The PubMed database was searched till August 2014 and 15 studies met the inclusion criteria. Fixed- or random-effects models were conducted according to study heterogeneity. We calculated the pooled relative risks (RR) for cancer risk or mortality along with 95% confidence intervals (CI).

RESULTS

Prophylactic bilateral salpingo-oophorectomy (PBSO) and bilateral prophylactic mastectomy (BPM) were both associated with a decreased breast cancer risk in BRCA1/2 mutation carriers (RR, 0.552; 95% CI, 0.448-0.682; RR, 0.114; 95% CI, 0.041-0.317, respectively). Similar findings were observed in BRCA1 and BRCA2 mutation carriers separately. Moreover, contralateral prophylactic mastectomy (CPM) significantly decreased contralateral breast cancer incidence in BRCA1/2 mutation carriers (RR, 0.072; 95% CI, 0.035-0.148). Of note, PBSO was associated with significantly lower all-cause mortality in BRCA1/2 mutation carriers without breast cancer (HR, 0.349; 95% CI, 0.190-0.639) and those with breast cancer (HR, 0.432; 95% CI, 0.318-0.588). In addition, all-cause mortality was significantly lower for patients with CPM than those without (HR, 0.512; 95% CI, 0.368-0.714). However, BPM was not significantly associated with reduced all-cause mortality. Data were insufficient to obtain separate estimates of survival benefit with PS in BRCA1 or BRCA2 mutation carriers.

CONCLUSIONS

BRCA1/2 mutation carriers who have been treated with PS have a substantially reduced breast cancer incidence and mortality. Clin Cancer Res; 22(15); 3971-81. ©2016 AACR.

Contralateral breast cancer risk in relation to tumor morphology and age-in which patients is preoperative MRI justified?

Identification of patients who are at increased risk for contralateral breast cancer is essential to determine which patients should be routinely screened for contralateral breast cancer using MRI. The aim of this study was to assess the association of age and tumor morphology with contralateral breast cancer incidence in a large, nationwide population-based study in the Netherlands. All patients with breast cancer stage I-III, diagnosed between 1989 and 2009, were selected from the Netherlands Cancer Registry. The association between contralateral breast cancer risk with tumor morphology and age was assessed using competing-risk regression according to Fine & Gray. Overall, 194,898 patients were included. In multivariable analyses, lobular tumors were significantly associated with an increased risk of contralateral breast cancer within 6 months (cumulative incidence 1.9 %, subdistribution hazard ratio (SHR) 1.17, 95 % confidence interval (CI) 1.06-1.30 compared with 1.3 % in ductal tumors, p = 0.002). Age was also associated with an increased risk of contralateral breast cancer within 6 months (SHR 2.34, 95 % CI 2.08-2.62, p < 0.002 for patients over the age of 75 as compared to patients younger than 50 years). The absolute risk of contralateral breast cancer within 6 months is only slightly increased in patients with a lobular tumor and older patients. In our view, this small increased risk does not justify standard use of preoperative MRI based on tumor morphology or age alone. We propose a more personalized strategy in which additional risk factors (family history, prognosis of primary tumor, and others) may play a role.

Better contralateral breast cancer risk estimation and alternative options to contralateral prophylactic mastectomy

The incidence of contralateral prophylactic mastectomy (CPM) has increased among women with breast cancer, despite uncertain survival benefit and a declining incidence of contralateral breast cancer (CBC). Patient-related reasons for undergoing CPM include an overestimation of the risk of CBC, increased cancer worry, and a desire to improve survival. We summarize the existing literature on CBC risk and outcomes and the clinical benefit of CPM among women with unilateral breast cancer who have a low-to-moderate risk of developing a secondary cancer in the contralateral breast. Published studies were retrieved from the MEDLINE database with the keywords "contralateral breast cancer" and "contralateral prophylactic mastectomy". These include observational studies, clinical trials, survival analyses, and decision models examining the risk of CBC, the clinical and psychosocial effects of CPM, and other treatment strategies to reduce CBC risk. Studies that have evaluated CBC risk estimate it to be approximately 0.5% annually on average. Patient-related factors associated with an increased risk of CBC include carriers of BRCA1/2 mutations, young age at breast cancer, and strong family history of breast cancer in the absence of a BRCA1/2 mutation. Although CPM reduces the risk of CBC by approximately 94%, it may not provide a significant gain in overall survival and there is conflicting evidence that it improves disease-free survival among women with breast cancer regardless of estrogen receptor (ER) status. Therefore, alternative strategies such as the use of tamoxifen or aromatase inhibitors, which reduce the risk of CBC by approximately 50%, should be encouraged for eligible women with ER-positive breast cancers. Future research is needed to evaluate the impact of decision and educational tools that can be used for personalized counseling of patients regarding their CBC risk, the uncertain role of CPM, and alternative CBC risk reduction strategies.

Reflections on screening mammography and the early detection of breast cancer: A Countercurrents Series

A little learning is a dangerous thing.[...]

Survival analysis of contralateral prophylactic mastectomy: a question of selection bias

BACKGROUND

Rates of contralateral prophylactic mastectomy (CPM) in women with breast cancer have increased, but most studies fail to show a survival benefit. We evaluated survival among CPM patients compared to patients undergoing single mastectomy (SM).

METHODS

The Surveillance, Epidemiology, and End Results database was used to identify unilateral breast cancer patients who underwent mastectomy with/without CPM from 1998 to 2010. Case-control analysis was performed with CPM cases matched to SM controls on the basis of age group, race/ethnicity, extent of surgery, grade, T classification, N classification, estrogen receptor status, and propensity score. Survival analyses included Kaplan-Meier curves and univariate and multivariate proportional hazard models to determine factors associated with disease-specific (DSS) and overall survival (OS).

RESULTS

A total of 26,526 CPM patients were identified. On multivariate regression analysis, increasing age, greater extent of surgery, increasing T and N stage, African American race, Hispanic ethnicity, poorly differentiated grade, and estrogen receptor negativity were associated with increased risk of death. CPM was associated with improved DSS (HR 0.86, 95 % CI 0.79-0.93) and even greater OS (HR 0.76, 95 % CI 0.71-0.81) compared with SM. Contralateral breast cancer (CBC) occurred in 1.6 % of women in the cohort. Removing CBC cases from analysis had little impact on CPM DSS (HR 0.86, 95 % CI 0.79-0.93) and OS (0.77, 95 % CI 0.72-0.82) suggesting that prevention of CBC by CPM does not explain the observed survival benefit.

CONCLUSIONS

CPM rates continue to rise. The improved DSS and OS observed with CPM support selection bias. Prospective trials are needed to determine cohorts of patients most likely to benefit from CPM.

Risk of multiple primary malignancies following treatment of Hodgkin lymphoma

Hodgkin lymphoma survivors who developed a second malignancy remain at high risk of developing subsequent malignancies. Treatment options for these malignancies may be more restricted making early detection especially important to improving outcome.

Breast cancer "tailored follow-up" in Italian oncology units: a web-based survey

Purpose

Breast cancer follow-up procedures after primary treatment are still a controversial issue. Aim of this study was to investigate, through a web-based survey, surveillance methodologies selected by Italian oncologists in everyday clinical practice.

Methods

Referents of Italian medical oncology units were invited to participate to the study via e-mail through the SurveyMonkey website. Participants were asked how, in their institution, exams of disease staging and follow-up are planned in asymptomatic women and if surveillance continues beyond the 5^th year.

Results

Between February and May 2013, 125 out of 233 (53.6%) invited referents of Italian medical oncology units agreed to participate in the survey. Ninety-seven (77.6%) referents state that modalities of breast cancer follow-up are planned according to the risk of disease progression at diagnosis and only 12 (9.6%) oncology units apply the minimal follow-up procedures according to international guidelines. Minimal follow-up is never applied in high risk asymptomatic women. Ninety-eight (78.4%) oncology units continue follow-up in all patients beyond 5 years.

Conclusions

Our survey shows that 90.4% of participating Italian oncology units declare they do not apply the minimal breast cancer follow-up procedures after primary treatment in asymptomatic women, as suggested by national and international guidelines. Interestingly, about 80.0% of interviewed referents performs the so called “tailored follow-up”, high intensity for high risk, low intensity for low risk patients. There is an urgent need of randomized clinical trials able to determine the effectiveness of risk-based follow-up modalities, their ideal frequency and persistence in time.

Bilateral breast cancers

An increasingly large proportion of women with unilateral breast cancer are treated with bilateral mastectomy. The rationale behind bilateral surgery is to prevent a second primary breast cancer and thereby to avoid the resultant therapy and eliminate the risk of death from contralateral breast cancer. Bilateral mastectomy has been proposed to benefit women at high risk of contralateral cancer, such as carriers of BRCA1 and BRCA2 mutations, but for women without such mutations, the decision to remove the contralateral breast is controversial. It is important to evaluate the risk of contralateral breast cancer on an individual basis, and to tailor surgical treatment accordingly. On average, the annual risk of contralateral breast cancer is approximately 0.5%, but increases to 3% in carriers of a BRCA1 or BRCA2 mutation. Risk factors for contralateral breast cancer include a young age at first diagnosis of breast cancer and a family history of breast cancer. Contralateral mastectomy has not been proven to reduce mortality from breast cancer, but the benefit of such surgery is not expected to become apparent until the second decade after treatment. An alternative to contralateral mastectomy is adjuvant hormonal therapy (such as tamoxifen), but the extent of risk reduction is smaller (approximately 50%) compared to 95% or more for contralateral mastectomy. This Review focuses on the risk factors for contralateral breast cancer, and discusses the evidence that bilateral mastectomy might reduce mortality in patients with unilateral breast cancer.

Second malignancies after breast cancer: The impact of adjuvant therapy

Second malignant neoplasms (SMNs) are potentially life-threatening late sequelae of the adjuvant therapy for breast cancer (BC). The increased risk of SMNs is associated with adjuvant chemotherapy (development of secondary acute myeloid leukemia and myelodysplastic syndrome) and hormonal therapy (risk of uterine cancer secondary to tamoxifen treatment). Previous studies have demonstrated an increased risk of SMNs associated with alkylating agents, topoisomerase-II inhibitors, granulocyte-stimulating factors and estrogen receptor modulators. Furthermore, analytical investigations have demonstrated that BC patients may be at an increased risk of leukemia following chemotherapy. In addition, correlations between an increased dose of hormonal therapy and solid tumor risk have been identified. Considering the ongoing alterations in the treatment of BC, with respect to lowering the daily as well as the cumulative dose of chemo-therapeutic agents, it is anticipated that leukemias will have a considerably lower impact on BC survivors in the future. However, diligent follow-up is required to accurately evaluate the long-term risks associated with chemotherapy.

Are synchronous and metachronous bilateral breast cancers different? An immunohistochemical analysis aimed at intrinsic tumor phenotype

The biology and pathomechanism of bilateral breast cancers is not fully understood. We compared the morphological and immunohistochemical characteristics of primary tumors in patients with synchronous bilateral breast cancers and metachronous bilateral breast cancers, with special focus on intrinsic tumor phenotype.

METHODS

Tumor morphology and expression of 8 immunohistochemical markers were assessed in tissue microarrays containing primary breast tumor cores from 113 metachronous bilateral breast cancers and 61 synchronous bilateral breast cancers. Analyzed markers included hormone receptors (estrogen receptor, progesterone receptor), HER2, Ki67, cytokeratin 5/6, E-cadherin, vimentin and epidermal growth factor receptor. Cutoff levels are provided in the table.

RESULTS

Metachronous bilateral breast cancers tumors had lower estrogen receptor expression (p=0.047) and higher expression of cytokeratin 5/6 (p=0.017) and of vimentin (p=0.008); in multivariate analysis only vimentin retained the significance (p=0.01). Ten (13%) and 11 (26%) of metachronous bilateral breast cancers and synchronous bilateral breast cancers had luminal A phenotype, 39 (50%) and 15 (36%) were luminal B HER2-negative, 13 (17%) and 12 (28%) - luminal B HER2-positive, 3 (4%) and 2 (5%) - HER2-positive (not luminal), and 12 (16%) and 2 (5%) had triple negative phenotype (p=0.07).

CONCLUSION

Metachronous bilateral breast cancers, compared to synchronous bilateral breast cancers, are characterized by more aggressive phenotype, expressed by lower expression of estrogen receptor and stronger expression of cytokeratin 5/6 and vimentin; this does not, however, translate into differences in the distribution of intrinsic tumor phenotypes.

Effect of taxane-based neoadjuvant chemotherapy on fibroglandular tissue volume and percent breast density in the contralateral normal breast evaluated by 3T MR

The aim of this study was to evaluate the change of breast density in the normal breast of patients receiving neoadjuvant chemotherapy (NAC). Forty-four breast cancer patients were studied. MRI acquisition was performed before treatment (baseline), and 4 and 12 weeks after treatment. A computer-algorithm-based program was used to segment breast tissue and calculate breast volume (BV), fibroglandular tissue volume (FV), and percent density (PD) (the ratio of FV over BV × 100%). The reduction of FV and PD after treatment was compared with baseline using paired t-tests with a Bonferroni-Holm correction. The association of density reduction with age was analyzed. FV and PD after NAC showed significant decreases compared with the baseline. FV was 110.0 ml (67.2, 189.8) (geometric mean (interquartile range)) at baseline, 104.3 ml (66.6, 164.4) after 4 weeks (p < 0.0001), and 94.7 ml (60.2, 144.4) after 12 weeks (comparison with baseline, p < 0.0001; comparison with 4 weeks, p = 0.016). PD was 11.2% (6.4, 22.4) at baseline, 10.6% (6.6, 20.3) after 4 weeks (p < 0.0001), and 9.7% (6.2, 17.9) after 12 weeks (comparison with baseline, p = 0.0001; comparison with 4 weeks, p = 0.018). Younger patients tended to show a higher density reduction, but overall correlation with age was only moderate (r = 0.28 for FV, p = 0.07, and r = 0.52 for PD, p = 0.0003). Our study showed that breast density measured from MR images acquired at 3T MR can be accurately quantified using a robust computer-aided algorithm based on non-parametric non-uniformity normalization (N3) and an adaptive fuzzy C-means algorithm. Similar to doxorubicin and cyclophosphamide regimens, the taxane-based NAC regimen also caused density atrophy in the normal breast and showed reduction in FV and PD. The effect of breast density reduction was age related and duration related.